Tag-use antenna and tag using the same

Abstract

The present invention relates to a tag-use antenna allowing a miniaturization while maintaining a constant minimal change of a communication distance. The tag-use antenna has a feed part of a folded dipole antenna of a size of 53 mm long and 7 mm wide being connected to, and equipped with, an LSI chip of Rc=500 ohms and Cc=1.4 pF and is covered with plastic resin 13 of the dielectric constant εr=3 and thickness of t=0.75 mm on both sides of the antenna. The dipole part of 1 mm wire path width of the tag-use antenna is formed in a rectangular spiral by being bent inward from both ends at bending parts at four places. The entire length of the dipole antenna when extending the four bending parts straight is featured so as to be shorter than one half of a resonance wavelength of the antenna. An inductance part is featured in the intermediate part of the both dipole parts in the neighborhood of the center of the antenna. The inductance part is connected to the chip equipment part in parallel with the both dipole parts.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an ultra-miniature, tag-use antenna used for a large-scale integration (LSI) chip and a tag using it for use in a radio frequency identification (RFID) system which is capable of carrying out a communication between a reader / writer and a tag by using a radio high frequency signal.[0003]2. Description of the Related Art[0004]An RFID system is one for transmitting a signal of approximately one watt from a reader / writer (simply “RW” hereinafter), receiving the signal on a tag side and retransmitting a response signal back to the RW side, by using an ultra high frequency (UHF) between 860 MHz and 960 MHz, thereby enabling the RW to read information stored in the tag.[0005]The tag is constituted by a tag-use metallic antenna formed on a flat surface such as a sheet or a film, et cetera, of approximately 0.1 mm thick, and an LSI chip connected to a feed point of the tag-use antenna. The LSI ch...

AI Technical Summary

Benefits of technology

[0041]The present invention is contrived to enable a provision of an extremely compact, tag-use antenna of which a communication distance is changed little by a body on which the antenna is attached to, that is, the antenna maintaining a minimally changed communication distance, and of a tag using the tag-use antenna.

Problems solved by technology

As such, a practicality is hampered if a communication distance of the antenna fluctuates when being attached onto various kinds of bodies, that is, when the operating frequency is displaced, and therefore desired is an antenna whose communication distance does not change even if it is attached to various kinds of bodies.

This is faced with practical problems.

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